Amethyst_Hat, a long, long time ago, Cisco produced several generations of underperforming, underfeatured, and generally underwhelming GigE switches. Extreme and Foundry produced switches that performed, had great features, and their software and reliability were good enough.
Since then, Cisco has caught up and is producing switches that are competitive in performance and features (still overpriced, but they are the market leader and they get to do that), while both Extreme and Foundry lost their ways as companies. Foundry got bought by Brocade, which I think is actually working out okay. Extreme is not doing so well.. years ago, they came out with a completely new software OS and completely new hardware based on completely new chipsets, and have never quite gotten back to their heyday. For example, I've heard nothing good from people who have used their X series switches in production environments.
If I were designing what you're saying you're designing, my inclination would be to use a Cisco or Juniper switch layer, and then look at someone like Aruba for a controlled/managed Wifi product. I would not try to get it all from one vendor.